Mulch
calculator
Bed area times depth, divided by 324, that's cubic yards of mulch. Enter the bed and the depth you want, and get the bulk order or the bag count.
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Where 324 comes from
A cubic yard covers 324 square feet at one inch deep (27 cu ft × 144 in²/ft² ÷ 12). So area times depth-in-inches, divided by 324, is yards, the formula landscapers use at the counter.
The right depth
2–3 inches is the sweet spot for beds: enough to suppress weeds and hold moisture, not enough to suffocate roots. Around trees, keep mulch pulled back from the trunk, the "volcano" pile against bark invites rot and pests. Fine mulches lean toward 2 inches; coarse bark can go 4.
Bags or bulk?
A cubic yard equals 13½ two-cubic-foot bags. Past roughly one yard, bulk delivery usually wins on price, bags win on cleanliness and moving them through a house. Odd-shaped beds: get the area from the square footage calculator first (circles and triangles included).
Mulch FAQ
Multiply bed area (sq ft) by desired depth (inches) and divide by 324 for cubic yards. 200 sq ft at 3 inches is 1.85 yd³.
13½ of the common 2 cu ft bags, or 9 of the 3 cu ft size. Beyond about a yard, bulk delivery usually beats bags on price.
2–3 inches for most beds, enough for weed suppression and moisture retention without smothering roots. Keep it off tree trunks and plant stems.
Top-ups count what remains: if an inch of old mulch survives, adding 1–2 inches restores the bed. Calculate with just the depth you're adding.